Power distribution networks include safety and protective equipment designed to protect the network and allow maintenance crews to quickly identify and repair faulty components. Such secondary power devices often require a dependable and stable power supply.
Powering these intelligent devices directly through wired means is often times difficult due to the high potential difference between power line and protective equipment. This issue is often referred to as “insulation coordination”, wherein unwanted flashover is avoided between the line, which is at line potential (e.g. 11 kV) and the secondary device that may be at ground potential (i.e., close to 0V). A multitude of standards (e.g. IEC, ISO and ANSI) dictate the required clearance between a line and any other object. Thus, extending a wire from a scavenging unit on the high voltage line to the secondary device could have serious implications when trying to maintain the two voltage levels (e.g. 11 kV and 0V).
In lieu of hard wired power means, batteries have been employed to power these secondary power devices. However, batteries suffer from drawbacks as well. Secondary power devices, due to possible remote placement, typically require batteries that have a small profile and a long life. In some instances such functionality is not possible, and in others, the cost is prohibitive.
There is, therefore, a need in the art for an alternate approach to powering secondary power devices that is dependable and cost effective.